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California Biodiversity Council:
An Applied Definition of Biodiversity1
What is biodiversity?
Biological diversity, or the shorter "biodiversity," (bio-di-ver-si-ty) simply means the
diversity, or variety, of plants and animals and other living things in a particular area or
region. For instance, the species that inhabit Los Angeles are different from those in San
Francisco, and desert plants and animals have different characteristics and needs than
those in the mountains, even though some of the same species can be found in all of those
areas.
Biodiversity also means the number, or abundance of different species living within a
particular region. Scientists sometimes refer to the biodiversity of an ecosystem, a
natural area made up of a community of plants, animals, and other living things in a
particular physical and chemical environment.
In practice, "biodiversity" suggests sustaining the diversity of species in each ecosystem
as we plan human activities that affect the use of the land and natural resources.
Why is biodiversity important?
Everything that lives in an ecosystem is part of the web of life, including humans. Each
species of vegetation and each creature has a place on the earth and plays a vital role in
the circle of life. Plant, animal, and insect species interact and depend upon one another
for what each offers, such as food, shelter, oxygen, and soil enrichment.
Maintaining a wide diversity of species in each ecosystem is necessary to preserve the web
of life that sustains all living things. In his 1992 best-seller, "The Diversity of Life,"
famed Harvard University biologist Edward O. Wilson -- known as the "father of
biodiversity," -- said, "It is reckless to suppose that biodiversity can be diminished
indefinitely without threatening humanity itself."
1
http://ceres.ca.gov/biodiv/Biodiversity/biodiv_definition.html
Evolution and Biodiversity in California2
by Robert L Bowman
Excerpt from California's Wild Heritage; Threatened and Endangered Animals in the Golden State, by
Peter Steinhart, reproduced with permission.
CALIFORNIA IS ONE OF the most biologically diverse areas in the world. Within its 160,000 square
miles, California harbors more unique plants and animals than any other state. The diversity of climates
and landscapes, and all the barriers to migrations such as rivers, mountains, and deserts, have led over
thousands of years to the evolution of a large number of isolated species and varieties of animals, many of
which are found only here. For example, there are about 30,000 species of insects recorded from
California, 63 freshwater fishes, 46 amphibians, 96 reptiles, 563 birds, 190 mammals, and about 8,000
plants.
Yet it is also true that today, California's extraordinary diversity is being lost in many important habitats
throughout the state. On average, over 20 percent of the naturally occurring species of amphibians,
reptiles, birds, and mammals are classified as endangered, threatened, or "of special concern" by agencies
of the state and federal governments.
Why does California have more endangered species than any other state? Biologists believe that the basic
cause is an ever-increasing human population that is degrading the environment at an ever-accelerating
rate. Many of California's unique species live in restricted habitats, under special conditions to which they
have been adapting for hundreds or thousands of years. As people change or destroy these habitats, their
native inhabitants die or fail to reproduce.
The Nature of Biological Diversity
WHEN WE SPEAK 0F "biodiversity," we imply more than just the variety of life forms around us. Each
species plays a distinct role in its own biotic community, and carries distinct genetic potential encoded in
its genes. This legacy of organic evolution is the basis and foundation of Earth's wealth. An understanding
of ecology, the study of ecosystems - the interrelationships between biotic communities and their physical
environments - is basic to effective conservation.
Nature's creativity is evident in the delicate interrelations among organisms within natural communities.
In the few remaining old-growth forests of the Sierra Nevada and other mountainous regions as far south
as San Diego, the reclusive spotted owl nests in the tops of the oldest trees. The vernal pools of the
Sacramento Valley are home to several species of ephemeral flowers, specially adapted to seasonal
fluctuations between standing water and aridity. Through their feeding and burrowing habits, three
common rodent grazers, the common ground squirrel, Valley pocket gopher, and the California vole - all
widely regarded as "pests" - can make significant contributions to both the quantity and quality of the
grassland vegetation of the Central Valley. Above-ground grazing by these animals encourages seed
dispersal, while burrowing promotes soil turnover and aeration. The burrows provide retreats for many
kinds of invertebrate animals, and the rodents themselves are food for larger predators such as blackshouldered kites, gopher and garter snakes, and great egrets. There are intricately woven patterns of
support that integrate living things into a functional community. If any one of the threads is broken, the
fabric of the entire system is threatened.
2
http://ceres.ca.gov/ceres/calweb/biodiversity/evolution.html
1. Biodiversity: What is it, where is it, and why is it important?
1.1 What is biodiversity?
1.2 Where is biodiversity?
1.3 What is the link between biodiversity and ecosystem services?
1.1 What is biodiversity?
Biodiversity is a contraction of biological diversity. It reflects the number, variety and variability of living
organisms and how these change from one location to another and over time. Biodiversity includes
diversity within species (genetic diversity), between species (species diversity), and between ecosystems
(ecosystem diversity).
Biodiversity is important in all ecosystems, not only in those that are "natural" such as national parks or
natural preserves, but also in those that are managed by humans, such as farms and plantations, and even
urban parks. Biodiversity is the basis of the multiple benefits provided by ecosystems to humans.
Biodiversity is difficult to quantify precisely even with the tools and data sources that are available. But
precise answers are seldom needed to sufficiently understand biodiversity, how it is changing, and the
causes and consequences of such change.
Various ecological indicators, such as the number of species in a given area, are used to measure different
aspects of biodiversity. They form a critical component of monitoring, assessment, and decision-making
and are designed to communicate information quickly and easily to policy-makers. However, no single
indicator captures all the dimensions of biodiversity.
http://internt.nhm.ac.uk/eb/homepage.shtml
INTRODUCTION
Biodiversity refers to the incredible variety of life found in our planet. In the book Biodiversity II,
Edward O. Wilson defines biodiversity as: "all hereditarily based variations at all levels of
organization, from the genes within a single local population or species, to the species composing all
or part of a local community, and finally to the communities themselves that compose the living
parts of the multifarious ecosystems of the world." Life on earth is so diverse that we really have no
idea how many species there are. Estimates range between 5 million and 30 million, but some
biologists believe the figure may be as high as 100 million. Biodiversity is central to our existence.
We derive much of the food we eat from species that were once wild, and we continue to rely on wild
species to genetically improve domestic varieties of corn, tomatoes, and other food staples. We also
use plants and animals found in natural ecosystems to develop new drugs for the treatment of
various diseases. In addition, biodiversity provides us with many ammenities, such as bird-watching,
ecotourism, fishing, and others. Despite the value of biodiversity to humans, we are currently
destroying natural ecosystems at such a rate that many biologists fear that in a few decades we will
cause an unprecedented number of extinctions. We are so far from cataloguing the diversity of life
on Earth that an unknown number of animals and plants will become extinct and we'll never know
what we lost. This is especially true of tropical forests and coral reefs, which we are losing
particularly fast. These ecosystems are mostly in developing countries, which face many important
challenges related to high debt burdens, poverty, social inequality, and population growth. Despite
the grim outlook in some areas, there are many ongoing efforts to help preserve our natural
heritage. Below you will find essays related to biodiversity, links to web sites with lots of information
about what you can do to help save biodiversity, and some really good references if you want to
read more about this subject.